Method of making watchcases



us H. COOK METHOD OF MAKING WATCHCASES HARRY COOK Filed Nov. 9, 1925 i.

l lllll llgmmm INVENTOR Patented Aug. 2, 1927.

PATENT OFFICE.

UNITED STATES HARRY COOK, OI SAG HARBOR, NEW YORK, A SSIGNOR T JOSEPH FAHYS & (30., OF NEW YORK, N. Y., A CORPORATION OF. NEW YORK.

METHOD OF MAKING WATCHGASES.

Application filed November 9, 1925. Serial No. 67,880.

This invention relates to watch-cases where the case has exterior lugs for the purpose of attaching a holding strap or the like as in the ordinary wrist watch. The invention has for its object the manufacture of such cases from filled stockwit-h their lugs spun or extruded from the same metal that forms the center piece of the case and simultaneously therewith.

It has been the general practice to make the lugs separate from the case and secure them thereto by soldering, brazing or other means. The result is not always satisfactory; the joint may not be perfect; it may show a difference in color or the lug may not set square or be symmetrical with the other lugs and the continuity of the precious metal may not be preserved. According to the present invention, I propose to make the lugs integral with the center piece of the watch-case by extruding them from the same blank that is used to form the center itself. Interior spinning is the pre ferred method of accomplishing this. An annular blank being inserted in a suitable die, the interior surface of which corresponds with the contour desired for the exterior of the center piece including the lugs thereon, the die is rotated and the metal of the blank expanded or extruded by a suitable spinning tool until the metal entirely fills the interstices in the die. The finished piece will then have the lugs integral with the case, the metal for forming them being drawn from the rest of the blank where such excess material is not required. The interior of the case, however, will still be circular and may have the usual hollow contour.

The more precious metal is retained in a thin but continuous layer of comparatively even thickness over the outside of a core of baser metal, the latter forming most of the bulk particularly in the lugs.

The invention will be more particularly described with reference to the accompany ing drawings in which Fig. 1 is a perspective view of a watchcase center piece extruded out of a single piece of material;

Figs. 2, 3, 4, 5, and 6 are cross-sectional views of a watch-case center of filled stock showing the successive stages of its manufacture;

Fig.7 is a sectional view of the die with a partially formed case therein; and

.Fig. 8 is an enlarged sectional view of a case lug.

Referring first to Fig. 2, there is shown a diametrical section of a disk of filled stock having a back of brass 1 and a surfaceof gold or other precious metal 2. The disk is in the next operation formed into the shape of av cup as shown in Fig. 3. The edges are then folded down as shown in Fig. 4 and the center punched out as shown in Fig. 5, leaving a torus-shaped blank with the precious metal covering the outer perimeter. The blank is then inserted in a revolvable die 3, as shown in Fig. 7 and an expanding tool 4: of proper shape presses the blank outward against the interior surface of the die sov that the metal, owing to its ductility, gradually flows into the interstices 5 and finally fills these interstices completely while keeping the interior of the blank circular. A case as finally formed is shown in section in Fig. 6 and in perspective in Fig. l. The lugs or ears may then be drilled as shown at 6 for the reception of a strapholding pin. The enlarged section of a lug (see Fig. 8) shows that the precious metal remains continuous all over the outside of the case and over the lugs, the bulk of the filling being made with the cheaper filling metal.

lVhile I have shown a preferred form of extruding the metal by means of a spinning operation, I do not wish to be confined in my claims to this particular means, as it is evident that other methods of extruding metal may be employed, as by hydraulic pressure, for example, or by stamping.

I claim 1. The method of making watch-case cen ters, which method consists in forming a substantially torus-shaped watch-case center blank, in arranging said blank within a die provided with a lug-forming recess, and finally in flowing the metal from the inturned flanges of said torus-shaped blank into the peripheral body thereof by a combined axial and radial expansion and in con tinuing the axial and radial expansion of the blank to flow the metal of said blank into said lug-forming recess.

2. The method of making watch-case centers, which method consists in preparing a watch-case center blank without lugs but, containing sufiicient metal to enable said lugs to be forn1ed tl1'e1'ebn by the extrusion of metal from said blank when subjected to pressure, in arran nw said blank within a q a die having oppositel y-presented pairs of" parallel lug-forming recesses, and finally in applying to said blank a combined radial and axial expansion of the blank Within the die whereby lugs are integrally; formedqqnl the finished watch-case center by the extrusion of'metal from the blank into saidrea combined radial and axial pressure to said center shell to extrude metal from its folded periphery for filling saidi recessesi oflthe die.

r l. The method of making watch-case centers, which method consistsin forminga flat blank of substantiallyuniform thickness, in

shapingsaid b'lanlfltoa'cup-like form, in folding down the lateral edges of said cap to lieparallel to the bottom wall of said cup, inqnrnehing outm central portion of said bottom wall to form a torus-shaped blank, in plaeingsaid torus-shaped bank in a forming die provided with Iag-fOrmiBgreT- cesses, and finally iniapplymg a combined radial and axial expansion to said blank whereby'an outward extrusion of nietallfrom the flanges of said torusand from the pe- -,ripheral body thereof; causes a flowage of metal into said lug-forming recesses.

HARRY COOK. 

